FA-11870 / Search retrieval semantics / Member archive

Rank fusion uses incomparable raw scores · case 05

Rank fusion uses incomparable raw scores.

Member previewVariant 5 · 3 implementations · 6 checks per implementation

Case contract

Each input list contains unique [id,score] hits in ranked order. Fuse by sum(1/(offset+rank)) using one-based rank; return IDs descending by exact rational fused score, lexical ties. Offset is a positive integer.

Why this case matters

An offline deterministic retrieval model isolates this search contract from tokenization, storage, and network behavior.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
one versus two deep ranks	`["a", "y", "z", "b", "x"]`	`["a", "b", "y", "x", "z"]`	Failed

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